The Monster Hero
by EndlessVacuum
Summary: Heroes, adventurers, monsters, magic and Quirks are an absolute reality. Izuku Midoriya, is a young boy driven to make an extreme gesture after a life of suffering and abuse. Little does he know that his life will change forever and that he will find himself becoming a hero as he has always dreamed of. Just...not exactly the hero he had in mind. - Isekai!Izuku fic / Crossovers


**THE MONSTER HERO**

**Chapter 1: Death and Reincarnation**

The thirteen-year-old Midoriya Izuku was writing something in a notebook, sitting at his school desk while his classmates around him chatted about this and that. It was only the second day of the school year, however soon the first teacher would come in, a new one apparently, and he would start with the first lesson, which was history.

Izuku sighed slightly, hoping that at least this teacher was not like everyone else and that he didn't discriminate because of his Quirkless status. It wouldn't have been a novelty...

Just then, the door to the classroom opened and a man in his late thirties entered. He had short black hair and eyes of the same color, giving him a completely common appearance and not at all interesting. The man walked up to his desk while the class president called everyone to order. It took a few seconds, but in the end there was silence and the man showed a small smile.

"Good morning everyone, as you may already know, I will be your new homeroom teacher." he turned to write his name on the blackboard "My name is Mikami Satoru and I will handle most of the subjects from here until the end of the year. English, Japanese and Home Economics will be covered by other teachers."

After that brief introduction, Satoru took off his jacket and started calling the various students, raising his head each time to be able to associate a name to the face of the aforementioned student. When he had finished the list, he was silent for a few seconds before asking "Tell me, who among you knows the history of the Earth before the Quirks?"

Izuku and some other students raised a hand and, after a brief glance, Satoru pointed to a girl with glasses and dark hair "The world was different from how we know it and there were neither Quirks nor monsters, and humans lived in all parts of the planet."

The teacher nodded "Correct, and can you tell me how we got to this point?"

This time he pointed to a bald student across the room "Because of wars and various cataclysms...?"

Satoru realized that not even the student himself was sure of his answer and the teacher couldn't really blame him, after all only those who had the desire to study history to the end could know exactly what had happened. Looking around the classroom, he saw that none of the other students had a more complete answer, so he decided to start his lesson from that.

"As your classmate has already said, before the advent of Quirks and monsters, humans lived virtually all over the globe and there were no heroes or villains, or at least not as we know them today." Satoru told them with a calm voice, looking at each student's face "However, what happened in that period, and which today is unthinkable, were wars. Our ancestors could not spit fire, create ice from nothing, fly with the power of thought, and do all that sort of thing, so they themselves created a method of fighting, designing ever more lethal weapons. Ironically it is thanks to those weapons that the Quirks have appeared, as well as the monsters."

Satoru looked for a moment at the map of the world hanging on the wall behind him "Many years before the appearance of the Quirks, a war broke out on a global scale and biological and nuclear weapons were used in different areas of the conflict. Many studies and old documents state that over sixty percent of the world population perished in that war." most of the students looked at him with shocked eyes, having never known that detail "As a result of the use of those weapons, innumerable harmful chemical agents were dispersed throughout the planet which began to change over the years, absorbing those agents. As the human race began to grow again, after having been devolved in many ways, such as medicine and technology, the world changed drastically. Many areas, considered normal before the conflict, became those that today are known as 'Dangerous Zones' and in these areas life forms, completely different from those we humans were used to, began to develop."

"Are you talking about the monsters, Mikami-sensei?" asked a boy with a concerned look.

The man nodded "Yes, I'm talking about them. What do you know about these monsters?"

Again, some students raised their hands and Satoru pointed to a chubby girl in the front row "They are the enemies of humans and the heroes fight against them!"

Some students nodded to her reply while Satoru showed only a small smile "That is a very simplified and imprecise way to define them. Anyone else?" and at that moment he saw that only one student had his hand raised, so the teacher motioned him to speak.

Izuku took a deep breath before explaining what he knew "U-Uh...with 'monsters', t-two categories of non-humans are i-identified. The first is d-defined as 'demi-humans' and contains t-those monsters that resemble humans, s-such as Dwarves and Elves, w-while the second is defined as 'demons' and a-are all those monsters that don't fall into the f-first category, such as Goblins and Orcs. Apparently, of all t-these races, there are t-ten monsters so strong that they have been defined as Demon Lords, and a-all monsters don't have Quirks b-but are able to use w-what has been called 'magic'."

"Nice explanation, nerd." snickered Bakugo Katsuki from his seat, making the others chuckle, while Izuku blushed with embarrassment.

However, instead of laughing, Satoru nodded "Excellent answer, much more complete than the last one." he looked at the rest of the class "What your classmate said is true, from the first to the last word. The monsters are actually divided into these two categories, but the demi-humans are not defined so only by their physical appearance, but also because, from what has been discovered over the years, they have an intelligence equal to or greater than that of an average human. It has been speculated that, for example, the Dwarves are also technologically advanced compared to the other monsters, although they are still behind us."

"Excuse me Mikami-sensei, but if these monsters are so smart, why are they considered enemies?"

Satoru looked at the girl who asked the question "Because unfortunately humans have never been good at living with others. From what is written in the history books, the first negotiations between humans and demi-humans went very badly and since then there has been no way to remedy, although there have been several attempts. It is often reported how they caused the negotiations to fail, but I am fairly certain that even the humans of that time did something wrong."

"If these fucking demi-humans don't want to cooperate, why don't we go to them and blow them up?" asked Katsuki with a frown.

"Because, as mentioned by your classmate, they can use magic. Scientists from around the world have studied this phenomenon and come to the conclusion that this magic is the equivalent of the Quirks for us, only that we cannot learn to use it because our DNA does not react well precisely because of our mutations." explained Satoru looking at the blond student "On the other hand, the magic that many monsters can use is capable of causing massive damage like the most powerful among the Quirks. The reason why they don't attack us is that, most likely, they know of this as well as the fact that they are in clear numerical inferiority."

One student raised his hand "It's because of the monsters that adventurers exist, right?"

"More or less." said Satoru before writing something on the blackboard "As many of you will know, those who want to become heroes must go to specialized schools, such as UA, Ketsubutsu Academy, Shiketsu and many others. Many things are taught in these schools, including how to deal with villains but also monsters. Once they graduate, the heroes can choose two paths: to continue to be simple heroes, and consequently reach the level of pro-heroes, that is the best of the best, or they can become adventurers, a second category of heroes specialized in facing monsters and accomplish missions, called 'quests', in the Dangerous Zones." after finishing writing, he sat down again "Of course these two categories are not separate, as it is known that the pro-heroes are also called to help the adventurers in cases of emergency and vice versa."

After that, Satoru began to explain other things related to the appearance of the Quirks until the end of the hour. School subjects followed one another until late afternoon when the last bell of the day rang throughout the school and the various students began to leave the class to go home.

Although their English teacher had been out for several seconds, Izuku didn't get up from his chair, continuing to write something in a notebook while his classmates talked to each other as they left the classroom. However, a figure silently approached Izuku and stopped in front of his desk, but the young green-haired boy didn't notice until a hand hit the wooden surface creating a small explosion that startled Izuku.

"Well well well...what do we have here...?" said Katsuki with a scowl before taking the notebook from Izuku's hands "You're already writing all these notes on today's lessons? Not only are you a Deku, but you also want to show off in front of the new teacher?"

At his side, a boy chuckled "Well it's the only way he can get himself noticed, since he doesn't even have a Quirk!"

Izuku tried to take back his notebook, but Katsuki put it in his hands before creating another explosion that burned the paper almost completely, leaving it ruined and blackened. The blond then threw the ruined notebook out the window without hesitating a second "From all those things I've seen, it seems to me that you still want to become a hero or perhaps an adventurer." he put his hand on Izuku's shoulder, squeezing hard "And I think I told you to give up that dream because you will never be able to do anything. You are as useless as a monster, or rather a monster would help me to become famous after having been defeated by myself. You can't do that either."

Trembling, Izuku opened his mouth to reply but when Katsuki tightened the grip on his shoulder even more, he remained silent, lowering his gaze. The other two students who had stayed with them made unpleasant comments about Izuku and approached the door, but then Katsuki stopped "Now that I think about it, maybe there's a way for you to become a hero with a useful Quirk!" he slightly looked back "Mikami-sensei said that some monsters don't die but simply are reborn. Maybe it will work with you too, so why don't you try jumping off a roof?"

With a pale face, Izuku turned outraged towards him but Katsuki raised a hand, creating some explosions with a menacing face "Got something to say?"

In the end, Izuku could only stand still and tremble while the others went off laughing.

Soon after, Izuku picked up his burned notebook from the ground holding back tears. He had hopelessly hoped that the new school year would be different, and instead it was like the past one, maybe even worse. The only positive side was Mikami-sensei, who had shown no form of racism or discrimination against him.

Not a single day had passed without Katsuki having bullied him verbally or physically and for a young boy like him, it was really too much.

His frail mind had finally reached a limit.

His feet moved on their own as he clutched his burned notebook to the chest. In his mind, he remembered the various important moments of his life and, unfortunately for Izuku, they were all unpleasant except for when he first saw his idol, All Might. Slowly, he continued to walk for several minutes, regardless of where he was going.

When he finally stopped, Izuku looked up and saw that he was standing next to an old six-story building abandoned for several years. Funny, it almost felt like his body and his mind had already decided for him. His heart started beating wildly as he climbed those decadent flights of stairs, all the while continuing to think of something else.

'_I'm so sorry __M__om..._' Izuku thought with a grim face '_After __D__ad's death I decided that I would become the man of the house and that I would make you proud...and instead I can't even face a bully..._' an empty laugh came from his lips '_Maybe it's better this way...she always worried when she saw bloodstains or burns on my clothes...I hope that if I'm reborn with a Quirk I won't have these problems..._'

[_Confirmation complete. Constructing a body that does not require blood_]

[_Confirmation complete. Acquiring skill |Explosion Attack __Resistance__|...success_]

Izuku paused for a moment, looking behind him with confused eyes. Strange, he would have sworn he heard a computerized voice say some things about a body and a skill. Shaking his head, he continued to rise, then heard the rumbling of his stomach.

Another empty laugh came from his lips "I'm sorry...but I can't eat right now. What was that joke Dad often said? Ah...if I could, I would predate anything to satisfy you."

[_Confirmation complete. Acquiring __unique __skill |__Predator__|...success_]

That voice again, but this time Izuku ignored it and after a minute or so he reached the roof. Slowly he went to sit near the edge and watched the landscape with the sun that was slowly setting. Without realizing it, he began leafing through the ruined sheets of his notebook.

"I always wanted to be a hero...save people with a smile, just like All Might..." Izuku started crying silently looking at the design of one of his possible costumes "A-And now...and now...I can o-only watch heroes from afar and s-spend time analyzing their Quirks...l-like who knows how m-many other people."

[_Confirmation complete. Acquiring skill |__Observe__|...success_]

Shaking his head, he wiped his tears with the sleeve of his school uniform before looking at another costume, but this one had the 'peculiarity' of having a long wooden stick in its hand and being surrounded by fire, water, wind, earth and lightning. Izuku had seen several images and videos of monsters while using their magic, and some of them also used weapons to cast their spells, so he found himself once thinking about how he could use magic like them.

"Perhaps if it had been possible I could have become...not a magician or mage, those names are already used by some heroes and theirs is not magic...therefore, a sage perhaps?" said Izuku, trying that particular name a few times.

[_Confirmation complete. Acquir__ing unique__ skill |__Sage__|...success_]

That voice again...maybe he was just going crazy.

"Yes, Sage would be perfect...and maybe with so much effort I would have become something more...Great Sage maybe, like a pro-hero among the heroes." added Izuku with an empty chuckle.

[_Confirmation complete. __U__nique__ skill |__Sage__evolving...success. U__nique__ skill |__Sage__evolved into |Great Sage|_]

After a few minutes of silence, Izuku released a trembling sigh. Taking a pen from his backpack, he began to write a short letter to his mother, apologizing for not having lived up to her expectations and for a lot of other things. After the brief letter, he put the notebook and pen in his backpack before standing up and getting even closer to the edge of the roof, without any intention of stopping.

"I really hope...I can help someone in the next life...if there is..." whispered Izuku before not feeling anything under his feet, but only a strong gust of wind from below. Despite the speed with which he was falling, Izuku was able for a moment to open his eyes, noticing the beautiful sunset that would illuminate his last moments of life.

And then, it was only darkness.

.

.

.

[_All requirements have been met. Activation __unique __skill |Second Chance|_]

.

.

.

'_It's so dark..._' Izuku thought looking around, even though he wasn't very sure his eyes were open.

'_W-Where am I?_' a few seconds had passed since he had woken up in this darkness, yet he had no idea what was happening. Izuku remembered perfectly that he had jumped off the roof of that building and the sunset he had seen before this darkness.

'_I survived? Did anyone save me?_' for some strange reason, those thoughts created mixed emotions inside him. On the one hand, he was happy that someone had saved him (if that was the case) but on the other hand, he simply wanted to say that he wasn't even able to commit suicide.

'_Kacchan was right...I can't do nothing right..._' thought Izuku before remembering something, that computerized voice '_I seem to have heard it again and...what did it say? Skill? Second __C__hance...?_'

After a few seconds of reflection, Izuku had an intuition '_Wait...is it possible that skill is another way of saying Quirk? Then...then...I really used my Quirk! I have a Quirk!_' he would have jumped for the excitement, but in his joy he hadn't yet realized that he couldn't move his legs '_Second Chance...if the name indicates something, it's probably a second chance...maybe a second life? I still remember perfectly everything I've done in recent years. __But if it's a second life...it means that I'm really dead._'

The realization of what he had done slowly settled in his mind but Izuku immediately drove it away. He had no time to think about that, he had to first understand what had happened after he had activated his Quirk.

'_If we start from the assumption that my Quirk has given me new life, leaving me all the memories, then maybe now I..._' horror and fear fell upon him as his mind thought of different options, but one of them was the most preponderant.

Although very young, he knew how children were born.

'_I...I...I'm in a woman's belly?! Oh God! Oh God! OH GOD!_' panicking, Izuku finally realized that he couldn't move his limbs, in fact he didn't even feel them. The idea of being a fetus inside a complete stranger, which would later become his new mother, was driving him crazy but then, suddenly, he moved.

'_Uh...?_' Izuku was confused for a few seconds before trying that action again, managing to move again '_I...I moved?_'

That was strange. He could distinctly feel his body moving in the direction he wanted, yet he wasn't moving with the use of limbs. He didn't even know how to describe the feeling.

'_But if I'm really moving...then I'm not inside a woman's belly. It is not possible that there is all this space..._' thought Izuku with relief, even if that discovery brought another question with it '_If I can move, but I'm not a child who is yet to be born...what am I?_'

Moving further, Izuku winced slightly when he felt something touch his body and, strangely, managed to visualize a sort of outline of that object.

'_Under my belly...is it grass?_' thought Izuku with confusion '_I can't smell, see or hear...I can only feel with my body. __What about taste...?_' and without being sure of having a mouth at that moment, Izuku tried to eat the grass beneath him and, much to his surprise, he felt the grass disappear inside his body, as if it had melted.

'_Wait a minute..._' a looming feeling of anguish and anxiety seemed to swallow his mind '_This is not something a human could do!_'

After a few moments of panic, Izuku decided to try to understand how his body was made and so he decided to move forward, feeling again that strange sensation halfway between rolling and skidding. He then tried to move backwards, to the right and to the left, always getting the same feeling, until the image of a monster, that he had seen months before in a book, formed in his mind.

'_Y-You're kidding me...r-right?!_'

Izuku tried again to move, noticing how his body seemed almost elastic and, after a few minutes, he stopped trying.

Even though he didn't want to admit it, his Quirk had made him reincarnate into a slime.

Several emotions clashed in his mind at that moment. Countless questions followed each other without stopping and he couldn't answer any of them. For the first time since he was reborn, he thought about his mother and what she would say if she saw him right now. His first real thought was to laugh, but he realized that he had neither a mouth nor vocal cords (or anything like that) to produce sounds.

He was alone, in an unknown place and he was a monster, yet not just any monster, but a slime. A monster that was usually used as a moving target for soon-to-be-adventurers' exercises.

Stunned by all that series of revelations, Izuku began to wander in that unknown place, absorbing all the plants he found in his path. He couldn't even determine how long it had been since he came back to life, yet to him it seemed like endless hours.

However, those hours of wandering had had a beneficial effect on him. After one or two moments when he was on the verge of going mad, Izuku had accepted the fact of being a slime, albeit reluctantly. He also discovered that he was (probably) in a cave judging by the stalagmites he had encountered and by the completely rocky terrain. As far as his body was concerned, Izuku had noticed that cold and heat counted little for him, bumping into a rock caused no real damage since he could quickly self-regenerate and apparently he didn't need to sleep or eat.

The only real problem was...

'_It's so lonely here..._' thought Izuku while still wandering in that cave '_Even if absorbing grass helps pass the time, I can do nothing for the lack of company..._' then a doubt arose in his mind '_I wonder...where did all the grass that I ate go?_'

[_Answer. They are stored inside the unique skill |Predator|'s stomach sack_] said a computerized voice in his mind, frightening him [_Also, the current space used is less than one percent._]

'_Someone actually answered!_' Izuku looked around, remembering the same voice he had heard before his death '_W-Who are you?!_'

[_Answer. This is the unique skill |Great Sage|'s effect. Since the ability has adapted, it can now quickly answer you_]

'_U__nique skill |Great Sage|?_' repeated Izuku. Indeed, before his death, the voice had said something about skills '_Actually...what are these skills?_'

[_Answer. When growth is recognized by the World, occasionally one will obtain a skill_]

Izuku was confused by that explanation but his curious nature led him to ask other questions and soon he discovered that those 'skills' were abilities that were common among monsters, while humans were lacking in them as they had their Quirks.

[_However, humans who do not have a Quirk can acquire skills and learn to use magic_]

'_What?!_' Izuku was shocked. If that was right, then all the people who were Quirkless could learn magic from the monsters! The only problem was that the monsters were not at all inclined to share the secrets of magic. After another few minutes talking to that voice, Izuku started to move again, happy to finally have someone to talk to, until he arrived on the edge of what, apparently, had to be a huge hole and fell into the water below, slowly starting to sink.

'_Oh no! I'm going to die! I can't swim with this body!_' thought Izuku with a panicked voice '_Great Sage! How much air do I have left before drowning?!_'

[_Answer. A slime's body does not require oxygen_]

'_Now that I think about it...I don't feel any kind of pain..._' the former human then began to think of a way to get out of the water. His first idea was to get to the bottom, assuming there was one, and then go up a wall like a sea slug. However he discarded that hypothesis because it would have taken too long and he wasn't even sure he could go out that way.

'_Wait...Great Sage, can I also expel what I store in my stomach?_'

[_Answer. Yes, anything stored __inside the unique skill |Predator|'s stomach sack__ can be expelled at any time_]

'_Then I could store a large amount of water and then spit it out, using it as a kind of jet water!_' and without hesitating a second, Izuku swallowed a large quantity of water before implementing his idea.

The good news is that it worked, the bad news is that it worked too well.

Due to the excessive power with which Izuku had spit out the water, he was thrown out of the water like a bullet and then squashed against something extremely hard before slowly slipping to the ground.

[_Acquired skill |Hydraulic Propulsion|_]

'_That w-was f-far too d-dangerous..._' thought Izuku with his whole body trembling.

'_**Mmm...what do we have here?**_' suddenly asked a deep male voice, surprising the slime '_**Can you hear me, little one?**_'

'_W-What? Someone is speaking to me?! But it's not Great Sage..._' Izuku easily knew that someone was in front of him, yet he had no idea how to respond. He didn't even have a mouth! What would have happened if that person didn't appreciate a lack of response? What if they decide to attack him? He couldn't defend himself from what he didn't see! But maybe he could try to make them understand something with signs? But how?

'_**Woah there! Calm down, little one. You're thinking too fast, it's hard to keep up with you.**_' said the voice with an amused tone, surprising him again.

'_A-Ah I'm sorry! That's a habit of mine and...wait...did you just read my thoughts?_' asked Izuku with confusion evident in his mind.

'_**Of course I did. **__**This is the skill |Telepathy|.**_' said the voice as if it were the most obvious thing in the world.

'_I'm sorry that I can't talk, but right now I'm in a state where I can't even see what's around me. Um...if it's not asking too much, who are you?_'

'_**Mh...my name is...**_' the voice stopped in mid-sentence, as if thinking of something '_**Although, it's hard to converse with someone if you can't see.**_' Izuku had the impression that this person had just nodded '_**Alright, I'll help you see. Just don't be scared when you see my appearance.**_'

'_Would you really help me?!_'

'_**But of course! You see, there's a skill called |Magic Perception|. It allows you to perceive the surrounding magic essence.**_'

Izuku tilted his whole body '_Magic essence?_'

[_Answer. This world is covered with and full of magic essence. For example, the body of a slime can move because it absorbs magic essence_]

'_**If you're able to perceive the flow of magic essence outside of your body, then you'll get the skill and with that you'll be able to see and hear!**_'

'_I see...therefore this essence is found in the soil as well as in the air and being able to perceive the flow I can make up for my lack of senses such as hearing and sight. Perhaps by controlling this flow better I could listen to someone far away or maybe-!_'

'_**Hey hey, you're doing that thing again...and with your body is actually creepy.**_' noted the male voice with a sweatdrop clear in his voice.

'_S-Sorry!_' Izuku decided to try to perceive the so called flow of magic essence and, true enough, after a few seconds he could feel something floating around him '_Is this the so called magic essence?_'

[_Extra skill |Magic Perception| acquired_]

'_Eh?! J-Just like that...?!_'

[_In order to organize large amount of information, suggest activating _|Great Sage| _skill at the same time_] said the computerized voice [_Activate |Magic Perception|?_]

'_Y-Yes please!_' nodded Izuku and in the blink of an eye, the world seemed to be created around him, as if a powerful light had just driven all the darkness away, showing him the enormous complex of tunnels and caves in which he had wandered for who knows how long.

'_Ooooh incredible!_' Izuku looked around with joy '_I can see! I can really see!_'

'_**Seems like you did it, then let me introduce myself again!**_'

Remembering his benefactor, Izuku turned to the origin of the voice to thank that person, only to find himself facing teeth bigger than himself and a creature covered in black, blue and gray.

"**MY NAME IS ****KING**** DRAGON ACNOLOGIA!**" roared the enormous creature and the power of its roar was enough to liquefy Izuku, hurling him against a nearby rock "**I'M ONE OF THE FOUR TRUE DRAGONS IN THIS WORLD! FUAHAHAHAHAH!**"

'_Oh God! This is a dragon?!_' thought Izuku with his whole body trembling. He knew about the power of those monsters, capable of facing and keeping up with the best pro-heroes in the world.

"**Hey, didn't I tell you not to get scared?**" said Acnologia, staring at him with with completely white eyes which were quite disturbing in Izuku's opinion "**Now that you can see, do you mind telling me what you're doing here...? This cave is not famous for slimes and I am pretty sure I have never seen one since I was sealed in this place.**"

Izuku's first idea was to run away, however the calmer part of his mind reminded him that Acnologia had helped him despite being a stranger, and from what the slime could see, the huge dragon didn't seem willing to attack him. Taking a deep breath, metaphorically speaking, Izuku then began to explain to Acnologia how he had arrived at that place, hoping not to seem too absurd with his explanation.

After about an hour of explanation, the dragon tilted his head to one side "**So you are a human who has come back to life thanks to a****n**** unique skill, but you have been reincarnated as a slime?**"

'_Yes, pretty much._' now Izuku was hoping with all of himself that the dragon would not attack him, with Acnologia being aware of his past as a human.

"**I have to admit, at first I was skeptical but I can always tell when someone is lying to me and you're telling the truth, although it's a pretty crazy story.**" said Acnologia slightly shifting since the lover part of his body was trapped in some kind of crystal.

'_Uh...you...are not a-angry that I w-was a human?_'

"**Why should I? You humans, especially those you call pro-heroes, are among the few who try to fight openly when they see me! Even though I've been stuck here for several years, so I don't know what the situation is out there...**" sighed Acnologia with bored eyes.

'_I...I see...by the way, h-how did you end up here?_'

"**Many years ago, when I was still free to go around sowing destruction, I was challenged by a pro-hero.**" explained Acnologia looking at the ceiling of the cave "**She looked like a girl like any other, but she had an enviable power and after several days of struggle managed to weaken me enough to allow other heroes to seal me. Those things that you call Quirk****s**** would****n'****t have been enough to seal me, but a hooded figure was able to use two skills, |Absolute Severance| and |Infinity Prison|, to seal me permanently in this place.**"

Izuku nodded slightly before noticing that the tone of Acnologia had changed when he spoke of the pro-hero '_Is it possible that he lost because he was fascinated by that girl's beauty...?_'

"**H-How can you think of such a thing?!**"

That huge dragon was...sweating?

"**A-After all she was just a girl with a slender physique, and skin that looked incredibly soft...and her long hair floating in the wind as she avoided all my attacks...not to mention her magnetic eyes full of emotions...**" Acnologia coughed once "**No reason to be distracted by such a person!**"

Izuku stared at him for a moment '_I really want to believe him but..._' before actually asking '_Um...do you know which way the exit is?_'

"**Oh...are you going to leave so soon?**"

'_He's expressing lonesomeness right away!_' thought a shocked Izuku '_Is there any way to help you get out?_'

Acnologia looked at him with curious eyes "**You want to help me?**"

'_W-Well...yes! I m-mean...you helped me, right?_' part of Izuku knew that freeing such a dangerous monster was a bad idea, but the thought of being sealed alone for who knows how many years must have been a fate worse than death '_Help each other is what friends do, i-isn't it?_'

"**Friends?!**" shouted Acnologia, making the whole cave shake "**A slime actually wants to be friends with the ****King**** Dragon?!**"

Now Izuku had the idea of having gone too far '_I-If y-you d-don't want t-to, i-it's fine..._'

"**Are you an idiot?! Who said it's not okay?!**"

'_U-Uh? So do y-you agree w-with us being f-friends?_' asked Izuku with hope clear in his voice.

"**That's right...**" Acnologia looked away crossing his arms over the chest "**I-If you really want to that much...**" not hearing any response from Izuku, however, he looked down at the slime and was surprised to see what looked like tears sliding down his body "**Hey, are you okay?**"

'_Y-Yes, s-sorry...it's j-just t-that...no o-one has ever w-wanted to become m-my friend in r-recent years..._' sobbed Izuku though his voice seemed filled with joy.

"**The it's official...**" said Acnologia handing a claw to Izuku "**I'll become your friend.**"

'_T-Thank you! I'll b-be in your care!_' and after a brief but comfortable silence, Izuku returned to the previous question '_S-So, what are we going to do about this seal?_'

"**Do you really want to remove it?**"

'_But of course! You're a friend of mine, so I have to help you._' nodded Izuku before looking at the crystal '_Great Sage, how do we get rid of Acnologia's seal?_'

[_Answer. There __i__s now way_]

'_… eh?_'

[_It is impossible to destroy |Infinity Prison| with physical attacks_]

'_I-Is that so...? These skills are really incredible, they seem more useful than a Quirk._' thought Izuku before talking with Great Sage about a way to undo the seal, until he heard a low growl.

"**Hey, don't only talk to your own skill.**"

'_S-Sorry Acnologia!_' Izuku apologized before explaining what he had discovered '_It seems that the seal could be broken after analyzing both the inside and the outside of |Infinity Prison|._'

"**Mh I see...but my abilities were sealed within it at the same time, so I can't use them anymore.**" replied the King Dragon.

'_I'll just need you to give me information on this, it seems like my |Great Sage| could analyze it._'

"**Won't that take a long time?**" asked Acnologia arching a non-existent eyebrow "**I thought you wanted to leave this place quickly.**"

'_That's true but I can't leave you here..._' thought Izuku before asking '_U-Um...and if you entered my stomach sack? That way I could take you with me and analyze your seal at the same time._'

Acnologia stared at him for a moment but then he lowered the head and his whole body began to tremble slightly "**Kukuku...Kuhaha...KUHAHAHAHAHA!**"

'_Wasn't that the three stage laugh...?_' wondered Izuku sweat-dropping.

"**A very interesting idea! Very interesting indeed!**" he looked back at Izuku "**Very well! I'll leave everything in your care!**"

'_But...do you really want to believe me so easily?_'

"**Of course. Compared to staying here and being lonely, breaking the |Infinity Prison| together with you is much more interesting.**" explained Acnologia with before raising a claw "**But before that...let me give you a name, while you think of a name for the both of us too. Let's embed the same symbol in our souls!**"

'_But I've already a name, it's Midoriya Izuku._' replied Izuku but Acnologia shook his head.

"**That was your human name, now you're a new being. That's why you need a new name.**"

'_I...I see..._' Izuku then began to think about a name '_A name for both of us...like a last name? King Dragon...King...King...King..._' he looked up at his new friend '_How does Emperor sound? Would that be too casual?_'

"**WHAT A GOOD NAME!**" another roar almost threw Izuku away "**Starting from today I'll be Acnologia Emperor! And as for you...**" he pointed a claw at the slime "**You said your old name was Midoriya Izuku? Then, from today you'll be...Midori! You can use Midori Emperor as your name!**"

Izuku nodded, thanking him for the name. The fact that it was similar to his old last name was an appreciated bonus.

"**Then, take care my friend.**" Acnologia nodded back at him.

'_Try to quickly escape from |Infinity Prison|, okay?_'

"**Leave it to me! It won't be long until I meet you again.**" said the dragon before being absorbed by Izuku's skill. As soon as Izuku returned to its basic form as a slime, Great Sage asked him if he wanted to start analyzing |Infinity Prison|.

'_Of course! Please take care of it, Great Sage!_' and after receiving a brief confirmation, he again began to wander through those caves, now being able to observe the surroundings as if he had eyes again. After a few hours of wandering, however, he realized that he could not communicate with Acnologia in any way and the thought saddened him a little, having lost someone to talk to.

'_Well it doesn't matter, as soon as the seal is removed, I can talk to him again._' thought Izuku while getting out of a small lake. He had finally managed to control his method of movement in the water but, looking at a stalactite nearby, he decided to try another thing and, to his great joy, he managed to spit out a blade of water that cut the rock as if it were butter.

[_Acquired skill |__Water Blade_]

'_Good! Now I can defend myself from any monsters, hoping that there are not too strong creatures in the surroundings..._' thought Izuku using his new attack again before moving on.

After taking his hand, Izuku continued to wander in the direction in which, he hoped, the exit was located. Along the way, he absorbed countless plants, minerals and even a great deal of water, until he found himself in front of a huge metal door.

'_Well now...how can i open it?_' thought Izuku before hearing a loud moan coming from the door that slowly began to open, forcing him to hide behind a rock. Leaning out from behind his shelter, he was surprised to see three humans wearing costumes and different gadgets hanging from their belts.

"The guildmaster is really reckless. To actually send us to investigate the sealed cave!" huffed the only girl of the group.

"Don't worry." said one of the boys, the one with a sword on his back "Even if they say there's a dragon here, it's probably just an oversized lizard."

'_Those three are...adventurers._' thought Izuku looking at their gear 'S_ince many adventurers don't have Quirks suitable for battle, they are often equipped with different types of weapons...also that girl spoke of a guildmaster, those who supervise the other adventurers. If I remember correctly, in society their rank is equal to that of a pro-hero._' then he noticed a detail '_I can understand them...is it possible that we are in Japan? Yet there are no Dangerous Zones there..._'

[_Answer. Using |Magic Perception|, the sound waves with meaning were transformed into comprehensible sentences_]

'_Ah I see...I wonder if I should try to interact with them...but even if only one of them is like Kacchan, then I would be in big trouble._' and so, deciding that discretion was the best strategy, Izuku waited for the three adventurers to move away before going out through the door they had opened. Noting that, beyond the door, there were still tunnels, he decided to move faster in order to finally get out of there but, suddenly, he found himself in front of a big black snake with horns that seemed to form a crown on its head.

'_What is this monster?!_' thought Izuku but then, a voice in the back of his mind, suggested he say a single word '_Observe..._' and, as if by magic, a semi-transparent pop-up window opened in front of him.

* * *

**Name**

NONE

**Race**

King Serpent

**Skills**

\- Heat Sensing

\- Poison Mist Breath

\- Heat Resistance (Low)

* * *

'_Wow...I can get these information by simply looking at a monster?_' wondered Izuku before reading again the monster's skills '_Wait...Poison Mist Breath...?_'

Just at that moment, the snake opened its jaws and let out a thick black mist that approached Izuku, forcing him to avoid it. Looking over his shoulder, he saw with horror that the fog had corroded the ground.

'_Oh God...this is no joke!_' Izuku turned back to the snake, but this time he remained much more calmer '_Uh...now that I see it better, it's not so scary...it's just a big snake. Acnologia was much scarier at the beginning._'

Avoiding another wave of poisonous mist, Izuku managed to jump on the wall remaining attached to it before hurling a blade of water at the snake, beheading it with just one blade. The monster fell to the ground, leaving a stunned Izuku on the wall '_O-Oh...I...I didn't think |Water Blade| was that strong..._'

Izuku looked at the corpse of the monster he had killed and felt a sick feeling inside him, but he managed to ignore it. After all, even if killing was something he didn't appreciate, now he was a monster and couldn't hope to run away from the fighting forever.

[_Inform. Suggest using |Predator| to predate King Snake_] said the computerized voice, surprising the slime [After predating the target, through analysis, it is possible to learn the target's skills]

'_Really?!_' he could learn new skills just like that? Thus, without hesitating beyond, he devoured the body of the snake, then returning to his classic rounded shape.

[_Acquired skills |__Heat Sensing__| and |__Poison Mist Breath_] said the computerized voice [_Also, it is possible to "mimic" the analyzed target_]

'_Mimicry...? __So can I change shape to look like this snake?_' wondered Izuku with curiosity '_Let's try this out then._' and so his body began to change shape and was also surrounded by a light black mist, until his body became a near-prefect copy of the original '_T-This is surreal..._'

A slight noise caught his attention and, looking up, he saw a group of bats flying over his head. Having an idea, he used |Poison Mist Breath| to attack a bat, turning pale when he saw it partially melt, before devouring it.

[_Acquired skills |Bloodsucking| and |Ultrasonic Waves|_]

'_I really hope I never have to use the first skill..._' thought Izuku returning to his slime form '_Now that I've absorbed a bat, I can try to mimic its vocal organ. If __everything__ goes well I should be able to talk!_' and so, Izuku tried to talk, immediately realizing that it was more difficult than expected.

Having nothing better to do while wandering through those caves, the slime continued to exercise, absorbing the occasional monsters that tried to attack him, until the third day when...

"I'm Midori." Izuku was pleasantly surprised to hear his own voice, even though it was different from the one he had when he was still a human "I did it, Great Sage!"

[_Yes_]

Izuku sweatdropped "What an unimpressed reaction..."

[_…_]

After that pleasant news, Izuku continued to wander through those tunnels until he saw the light of the outside world and, without thinking twice, hopped in that direction, finding himself then in the middle of nature. The sight of this world so pure bewitched him instantly and Izuku found himself looking around with astonished eyes. Everything was so beautiful and alive. The absence of monsters in the vicinity also helped to give the whole a more peaceful and pleasant air.

Continuing to practice with his skills and his voice, Izuku went into that forest, wondering where this place was. From what he remembered, there were no Dangerous Zones in Japan and the closest was the one which occupied much of China, a part of Russia, all of Mongolia and part of Kazakhstan, yet he could not be sure until he spoke to humans.

Deciding to rest a little, even though he was not tired, Izuku used his ability |Steel Silk|, which he had obtained after absorbing a giant spider in the cave, to hang himself from a tree and start practicing his pronunciation, but after a few minutes, he heard a threatening growl near him.

Looking in that direction, Izuku noticed a small pack of dark-haired wolves with one of them that had a darker star on the forehead. The wolves still snarled but when Izuku dropped to the ground to try to understand their intentions, the whole pack ran away yelping with fear, leaving behind a very confused slime.

'_W-What happened?_' wondered Izuku before moving in that direction '_It seems like they were really afraid of me._'

His thoughts, however, were interrupted by a slight clamor and only at that moment did he notice about thirty figures that had stopped short of him. With a quick glance he realized that they were Goblins armed for a fight, yet their bodies were thin and seemed frail while their weapons were rusted and ruined. Honestly, although Izuku was nervous about their presence, they didn't even seem to be a serious threat to him.

"Guga strong one..." said one of the Goblin with a bandana, surprising Izuku "Did you have any business ahead of here?"

'_So they can talk...but I only know Japanese, so how can I communicate with them?_'

[_Answer. Through the same process used to understand the language of other life forms, the sounds that carry your thoughts can be used to communicate_]

'_Is that so? Then I'll try!_' nodded Izuku before forming a mouth in his slime body "H-Hello there! It's the first time we've met! U-Uh...I'm a slime, and my name is Midori Emperor!"

However, although he had the idea of having spoken in a normal way, he saw all the goblins tremble in fear before falling to the ground, with some of them kneeling as if they were facing their leader.

'_…eh?_'

"Guga strong one!" said the Goblin with the bandana "We've already fully recognized your strength so please, lower you voice!"

"My voice...?" repeated Izuku making them tremble even more. Was it possible that he had spoken so loudly? Or maybe his thoughts were too loud? He hadn't had these problems so far, but maybe it was because he hadn't yet tried to talk to other creatures other than himself and the wolves before had escaped even before he could speak.

But what Izuku had failed to notice was that he was mumbling again. Aloud.

Some of the Goblins had already lost consciousness and the others were on the verge of tears. The one with the bandana shouted to the others to escape with those who were unconscious and only when they were away did Izuku realize his mistake.

"W-Wait!" Izuku tried to hop behind them, but they were faster than him "I-I'm sorry! I'm not a bad slime!" but it was too late. He was alone. Again.

'_It's not my fault..._' Izuku thought with sadness in his heart. With Acnologia he had managed to make friends, but apparently it wasn't so easy with everyone.

'_Still...I wonder why those wolves ran away from me when I didn't even talk._'

[_Answer. There are no monsters with more magic essence than the individual named "Midori Emperor" in the surrounding hundred meters of area_] explained the computerized voice.

'_Is that so...? Does that mean they can use |Magic Perception| as well...?_' wondered Izuku before asking '_Great Sage, can you change my view__point of __|Magic Perception|? I want to look at myself._'

[_Understood_]

A moment later, Izuku was able to see his body from above and, in addition to discovering that his body was green, he saw a thick dark aura leaking from his body in all directions.

'_W-What is that...?!_'

[_Answer. That is your aura, perceptible to all monsters_]

'_It's so dark and...malevolent...no wonder why the wolves ran away..._' thought Izuku '_Great Sage, can I suppress my aura?_'

[_Answer. Yes_]

Izuku sweatdropped again. He also wanted to know how, but deciding to try it by himself, he focused on his aura and, slowly, he managed to suppress it entirely.

'_This should be good. Now I need to find those Goblins again..._' he looked around for a moment, noting that the forest was very dense and that the goblins had not left many traces.

"I don't know where they went and I'm alone in the middle of a forest..."

He sighed.

It was official. His second life as a slime sucked...

**TO BE CONTINUED...**

* * *

**This is a story I received from a friend, but he was no longer interested in it so I decided to start it myself! I hope you like the idea and, for those who will answer, what kind of names do you want for the canon characters of "That time I got reincarnated as a slime"? Because they have many different translations between them (for example Ligurudo, the head of the Goblin village, is also called Rigurd or Rigurudo).**

**Let me know in the reviews! Also, expect a lot of cross-over elements from different manga/anime/games, such as Acnologia (Fairy Tail)!**


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